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Figure 6 | EvoDevo

Figure 6

From: The Nodal signaling pathway controls left-right asymmetric development in amphioxus

Figure 6

Inhibition of Nodal signaling disrupts formation of the left-sided mouth and causes duplication of the right-sided pharyngeal structures in amphioxus larvae. (A, A’) Dorsal views of the pharyngeal region of B. lanceolatum L2 larvae stained for β-catenin and acetylated α-tubulin. ‘L’ indicates the left side and ‘R’ indicates the right side; anterior is to the left. Following administration of SB505124, the larvae exhibit loss of the preoral pit (pp, black arrowhead), the mouth (m, black arrow), and the first gill slit (fgs, white double arrow) and ectopic development of the club-shaped gland (csg, white arrow) and the endostyle (en, white arrowhead). (B-H, B’-H’) In situ hybridization of the treated B. lanceolatum larvae revealed loss of expression of Pitx, Lhx3, and Dkk1/2/4 and bilateral expression of Krox, FoxE4, FoxQ1, and Nkx2.1 concomitant with the duplication of the right side. (I-K, I’-K’) View from the left side displaying loss of the duct of the club-shaped gland (white double arrowhead) upon treatment with SB505124 as deduced from the expression of Krox, FoxE4, and Nkx2.1. (L-O, L’-O’) Transverse sections of B. floridae larvae through the pharynx showing the loss of Pitx expression concomitant with the loss of both the preoral pit (black arrowhead) and the mouth (black arrow) and the ectopic left-sided expression of FoxE4 and Nkx2.1 concomitant with the ectopic development of the dorsal part of the club-shaped gland (white arrowhead) and the endostyle (white arrow) after treatment with SB505124. (P, P’) Snapshots of the 3D model of B. floridae larva reveal consistent morphological changes with B. lanceolatum larvae for both the normal and treated embryos. The snapshots are taken from the left lateral view. Asterisks (*) mark the anterior. Green, preoral pit; yellow, mouth region; blue, endostyle; red, club-shaped gland; purple, gill slits. Scale bars, 25 μm.

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